Composite Lining of Tubulars as an Economically Sound Solution to Oilfield Corrosion

Tubular goods lined with Glass Reinforced Epoxy (GRE) composite liners have been used in corrosive service for 30 years and have gained worldwide acceptance as a solution to corrosion from salt water and exposure to acid-forming components of produced and injected fluids and gas. This acceptance is a direct unction of the material's durability and long product life. This ultimately provides the end user a lower cost alternative to expensive steel alloys and opens up new opportunities in corrosive gas production and gas-lifted oil production, where previously chromium-nickel alloys have been exclusive choices. Advanced variations of GRE can now be utilized in deep gas production and corrosive high-temperature injection service, both on- and offshore. The Cost of Corrosion The cost of corrosion can be in terms of capital expenditure and/or operating expenditure and is also reflected, to a large degree, as an impact on HSE (Health, Safety and Environment) considerations. Four cost categories are identified as follows:The cost of designing corrosion control into the project (e.g., the purchase of GRE-lined tubular products at a premium to less costly product);The cost of maintaining and repairing corrosion-damaged equipment (e.g., the costs of pulling and repairing failed tubing);The cost of replacing failed equipment (e.g., the cost of replacing a string of failed tubing); andThe consequences of lost revenue due to failed equipment (e.g., the financial impact of shutting in and working over an injection well). About $150B of the $300B (NACE estimates) in annual damage from corrosion can be prevented by the implementation of one or more methods. Construction of a barrier to corrosion within the tubular product is the simplest and arguably the most effective alternative, especially in downhole applications. Composite technology has evolved to the point of providing economically viable solutions to corrosion by forming a durable barrier between corrosive fluids or gases and the steel in service. Definition of Composite-Lined Tubulars Composites are defined as fibre-reinforced thermosetting or thermoplastic matrix materials. The introduction of composites into the oilfield has yielded the opportunity in many instances for operators to select lightweight corrosion-resistant alternatives to high-cost alloy steel. Applications include options for onshore (pipelines, tanks and storage vessels), offshore (injection lines, structures, and flowlines) and downhole (composite tubing and liners for installation into tubing). Lined tubulars consist mainly of mild steel tubing with standard oilfield connections lined with composites like GRE or thermoplastic materials such as High Density Polyethylene (HDPE) and Polyvinyl Chloride (PVC). The most historically effective coupling protection is provided by a Corrosion Barrier Ring. This ring is installed in the unlined area of the coupling as illustrated in Figure 1. Outperformance of HDPE and PVC by GRE in high temperatures or in gas-saturated environments has been a strong economic driver for the manufacture and installation of GRE in lined steel tubular goods.